Accepted name: squalene—hopene cyclase
Reaction: squalene = hop-22(29)-ene
Systematic name: squalene mutase (cyclizing, hop-22(29)-ene-forming)
Comments: The enzyme also produces the cyclization product hopan-22-ol by addition of water (cf. EC, squalene—hopanol cyclase). Hopene and hopanol are formed at a constant ratio of 5:1.
1.  Hoshino, T. and Sato, T. Squalene-hopene cyclase: catalytic mechanism and substrate recognition. Chem. Commun. (2002) 291–301. [PMID: 12120044]
2.  Hoshino, T., Nakano, S., Kondo, T., Sato, T. and Miyoshi, A. Squalene-hopene cyclase: final deprotonation reaction, conformational analysis for the cyclization of (3R,S)-2,3-oxidosqualene and further evidence for the requirement of an isopropylidene moiety both for initiation of the polycyclization cascade and for the formation of the 5-membered E-ring. Org Biomol Chem 2 (2004) 1456–1470. [PMID: 15136801]
3.  Sato, T., Kouda, M. and Hoshino, T. Site-directed mutagenesis experiments on the putative deprotonation site of squalene-hopene cyclase from Alicyclobacillus acidocaldarius. Biosci. Biotechnol. Biochem. 68 (2004) 728–738. [PMID: 15056909]
4.  Reinert, D.J., Balliano, G. and Schulz, G.E. Conversion of squalene to the pentacarbocyclic hopene. Chem. Biol. 11 (2004) 121–126. [PMID: 15113001]
[EC created 2002, modified 2011]